The present invention relates to a heat-bonding method. In particular, it relates to a method of heat-bonding thermoplastic materials to types of synthetic fabrics to which such materials could not heretofore be successfully bonded.
It is well established in the art that thermoplastic materials, such as polyvinylchloride, polyethylene and the like, can be heat bonded to one another and to a variety of substrates of various materials. The most commonly used method for effecting such a bond is Radio Frequency Bonding, where a dielectric field is impressed across an assembly of the materials to be bonded together. One of the electrodes carries a die having a raised design, and when the assembly is compressed between the electrodes the materials become welded or bonded together along the design lines of the die. Such a method is disclosed in U.S. Pat. No. 2,946,713 of P. Dusina, Jr. et al.
It is equally well known in the art, however, that all heat-bonding methods heretofore known are quite ineffective for producing a reasonably permanent bond between thermoplastic materials and certain types of synthetic fabrics. These fabrics are of a type having a dense weave, usually known as "plainweave". Such fabrics, usually--but not always taffeta--may be of nylon, polyester, rayon acetate or similar materials, and their weave is especially dense if the fabrics are woven of filament yarn.
Synthetic fabrics of this type are widely used in a variety of applications. They may be converted into articles of apparel, such as "windbreakers", lightweight sports jackets, sailing apparel, ski and racing apparel. Again, they are used in manufacturing children's wear, camping equipment such as lightweight tents, sails for boats, and many other items. It is in the nature of many of these applications that the fabric (or the item made of it) should be windproof and/or water repellent; for this reason, many of these fabrics are coated or impregnated with silicones or fluorocarbons in order to attain these desired characteristics.
It is very desirable to be able to heat bond thermoplastic materials to such fabrics, for example, in form of decorative appliques. Experience has, however, always shown heretofore that a reliable bond could not be obtained between these materials. While a slight bonding action was usually observed when prior-art methods were used, the lightest pull was sufficient to separate the applique from the base fabric. It is evident from the nature of the articles which are listed above by way of example, that many-- if not most of them--would have increased appeal if they could be provided with a decorative applique, for instance with a club badge on a ski jacket. Indeed, such articles are widely provided with appliques; however, in all instances these are appliques which are separately manufactured and which are then stitched onto the article. The use of heat-bonded thermoplastic appliques, which inherently would permit the application of a wider range of designs that could be applied at lower cost, has heretofore always been impossible.